This invention relates to a dry etching gas and a plasma processing method for a material to be processed using the gas.
A dry etching technique, which is capable of forming fine patterns in the production of IC, is utilized for the production of super LSI, etc. in lieu of wet etching.
For dry etching a semiconductor material such as silicon dioxide (hereinafter also referred to as SiO2), a mixed CF4 and H2 gas, CHF3, C2F6, C3F8, C4F8 or a mixture thereof is used as an etching gas for the purpose of sufficiently increasing an etching rate ratio of the SiO2 to silicon (hereinafter also referred to as Si) or polysilicon (hereinafter also referred to as polySi) on which the SiO2 is formed. The above fluorine-containing gases, such as CF4, CHF3, C2F6 and C3F8, however, have a long life in atmosphere and a large global warming potential. Namely, when discharged to air, these gases retain without being decomposed for a long period of time and contribute to warming of earth as a greenhouse effect gas (hereinafter referred to as GHG).
The global warming is the most important problem among various currently alarmed global environmental problems. Climatic Change Framework Treaty has been adopted 1992 for the prevention of global warming. Detailed methods of restricting GHG and schedule therefor are now discussed in meetings of contracting states of the Treaty.
To cope with the global warming problem, various methods for reducing GHG are investigated with the simultaneous development of various techniques for substitutes for GHG.
Up to now, however, no effective substitutes have been found for conventional etching gas for semiconductors. Thus, the current trend is toward the decomposition of exhaust gases discharged after etching steps so as to reduce the emission of GHG to air.
It is an object of the present invention to provide a dry etching gas which is free of global environment problems such as global warming and a plasma processing method for a material to be processed using the dry etching gas.
The present inventors have made an earnest study for solving the above-described problem and, as a result, have found that the problem can be solved by using an organic compound constituted of carbon, fluorine, hydrogen and oxygen and having 2-6 carbon atoms and thus completed the present invention.
Namely, according to the present invention, there is provided a dry etching gas comprising an organic compound constituted of carbon, fluorine, hydrogen and oxygen and having 2-6 carbon atoms.
The present invention also provides a plasma processing method for a material to be processed, characterized in that the material is processed with a plasma gas obtained from the above-described dry etching gas.